Physiological monitoring system

ABSTRACT

A physiological monitoring system for hospitalized patients wherein each of the patients monitored would be provided a patient monitoring unit which would electrically sense two or more physiological conditions, translate desired information into digital form and transmit it by pulse coded FM radio link to a central monitoring station. The central monitoring station would receive transmitted information from one or more patients so equipped and detect and display the information in analog and digital form and in some instances provide automatic alarms on the occurrence of certain predetermined values for the sensed conditions.

Unite States Patent Buxton et aI.

[ 1 Feh.29,1972

[54] PHYSIOLOGICAL MONITORING OTHER PUBLICATIONS SYSTEM Geddes et al.American Journal of Medical Electronics" 72 Inventors: Richard L.Buxton; George N. Miller, both pP- f H ill Al Kahn et al. AmericanJournal of Medical Electronics," Apr.-Jan. 1963,pp. 152- I57. [73]Assignee: Care Electronics, Inc. [22] Filed; A 6, 1969 Primary Examinerwilliam E. Kamm 1 pp 847 946 Attorney-C. A. Phillips ABSTRACT "128/ 128/A physiological monitoring system for hospitalized patients [.1 whereineach of the pa on to ed ould be Provided a [58] Field 055m! 128/2patient monitoring unit which would electrically sense two or 128/ Rmore physiological conditions, translate desired information intodigital form and transmit it by pulse coded FM radio link [56]References cued to a central monitoring station. The central monitoringstation UNITED STATES PATENTS would receive transmitted information fromone or more patients so equipped and detect and display the informationIn B0116 M analog and form and in some instances provide auto- 3,210,74710/1965 Clynes ..l28/2.l A m; alarms on the occurrence of certainpredetemined l\g ujilleumielr et al. ,.128/2.l A values for the sensedconditions a ev et a 3,465,103 9/1969 Lynch ..l28/2 l A 3Claims,4DrawingFigures LL, UlL,

TACH. 76 AND 74 P72 METER as s DRIVE PRE-SHOCK 'Q I DETECTOR 79 ECGA aALARM 78 DIGITOL TO ECG-B g) ANALOG Ewe TAPE flee CONVERTER ARTERAUDRECORDER i VElNAL-E l RECEIVER I l I l LOW HIGH 2 SYSTOLIC 8 2 B 3 i lIIIIIII 1 h 8 i 5 CONTROL BINARY TO "2 DIEggDE be, I 5 WORD 7 l 8CD R h88 DIASTOLIC I l 678 i i l CONVERTE DETECTOR 4 l 86 -Ek H4 H6 94 fldsPATIENT SELECTOR I234567BS D ID E G H [YATEfh 22 a GATE go/F GATE Os/lGATEl' fio Panel-I1 2 98 I00 I02 E lO4 l06 SYSTOLIC DIASTOLIC VElNALEXTERNAL INTERNAL PRESSURE PRESSURE PRESSURE TEMP TEMR IO l0 l0 PATIENTUNITS P-l P-2 P-3 P-4 P-5 P-6 P-7 P-8 CENTRAL MONITOR RECEIVERS RichardL.Buxton George N. Miller,

INVENTORS ORNEY PHYSIOLOGICAL MONITORING SYSTEM This invention relatesto measurement systems and particularly to a system for the measurementand display of physiological conditions.

Equipment for the measurement of physiological conditions by electricalsensing means has been developed to the point where extremely valuablemeasurements can be obtained of such things as, for example, cardiaccondition, blood pressure and temperature. However, a number of problemsexist with respect to existing apparatus, particularly in the area ofinterface between measurement equipment and the medical observer whomust, with a high degree of efiiciency, extract measured data and act onit. A further problem area lies in presently used means forcommunicating data between the person of the patient and the datareadout equipment.

Accordingly, it is a primary object of this invention to bridge the gapbetween the art of raw measurement of physiological conditions and thenormal abilities and frailities of persons charged with theresponsibility of continuously monitoring the physiological conditionsof a patient or, in most cases, several patients, and to provide anoverall system wherein the critical interface between a patientscondition and the monitoring doctor or nurse is much more effectivelyand efficiently achieved than heretofore.

It is a further object of this invention to provide for centralized orremote monitoring of conditions of a number of patients without thenecessity of wire linkage between the patients and the monitoringequipment; thus, freeing patients to move about without restraint andmaking unnecessary the substantial wiring that would be normallynecessary to construct such a monitoring system.

It is a further object of this invention to provide a system ofintensive care monitoring which does not require particular location ofpatients.

It is still a further object of this invention to provide the necessarycommunications link between a patient and central monitoring equipmentby radio means capable of dependable operation in a hospitalenvironment.

It is still another object of this invention to provide a patientmeasurement unit which may be operated with very low power consumptionpermitting relatively long periods of operation without the necessity ofreplacing battery power sources.

It is a still further object of this invention to provide for accuratedata resolution by means of the use of a particular form of digitallyencoded data.

In accordance with the invention, a plurality of patients, for example,eight patients, requiring intensive care are each equipped with ameasurement unit which electrically measures several physiologicalconditions pertinent to the ailment of the patient, for example, heartcondition, blood pressure and temperature. Electrical outputs from bodyprobes providing these measurements are fed through preamplifiers to acommutator which provides a single continuous output signal made up ofrepeated, serially arranged, samplings of the individual sensedconditions. Next a signal conditioner, operating in synchronization withthe commutator, selectively adjusts, as needed, the reference level ofthe now serially occurring physiological signals. After this, eachphysiological signal is translated into a digitally encoded word, whichtogether with appropriate synchronization information, is transmitted bya pulse-coded modulated FM transmitter to a central monitor. The centralmonitor receives transmissions on separate frequency channels from eachpatient unit and translates the transmitted data variously to achieveaccurate and optimumly presented reproductions of sensed physiologicalconditions. For example, heart and blood pressure data is translatedinto analog form and indicated by meter and cathode-ray display. Bloodpressure and temperature data is translated into decimal form anddirectly presented as decimal quantities on digital displays. Inaddition, an E.C.G. signal is analyzed for overvoltage output and apreshock state indicated by a warning signal. Similarly, systolic anddiastolic (high and low) arterial blood pressure excursions are detectedand a warning signal given if there is a departure from preset values.Diastolic and systolic blood pressure values are also presented indecimal form by gating a decimal readout, to display and hold high andlow blood pressure values.

These and other objects, features and advantages of the invention willbe readily appreciated from the following description when consideredtogether with the accompanying drawings in which:

FIG. 1 is a schematic illustration of the overall system of theinvention;

FIG. 2 is an electrical schematic circuit diagram of a patient worn unitof this invention;

FIG. 3 is an electrical schematic circuit diagram of the centralmonitoring unit of this invention; and

FIG. 4 is a view along the lines 4-4 of FIG. 3 illustrating thecathode-ray tube presentation provided by the circuit of FIG. 2.

FIG. 1 generally illustrates the system of the invention as applied toan intensive care application in which eight patients are monitored by asingle medical observer. Each patient is equipped with a patientmeasurement unit 10, designated P1- P8. The patients may be in separaterooms, making unnecessary a special location for patients requiringintensive care. Central monitoring unit 12 is functionally divided, ingeneral, into Receiver Section 14, Every Patient Continuous Monitoring"(EPCM) section 16, Patient Selective Monitoring" (PSM), section 18 andCathode-Ray Display (CRD), section 20. In the Every Patient ContinuousMonitoring" section there is continuous monitoring of systolic bloodpressure, heart rate and continuous monitoring for preshock indications.There is also selectable continuous monitoring of any one of severalconditions.

FIG. 2 generally illustrates the circuit arrangement of patient unit 10.ECG, electrocardogram, electrodes 22, 24 and 26 together with ground orreference electrode 28 are appropriately positioned in contact with apatient and function to pick up electrical potentials or signalsgenerated by the heart. These signals, labeled A, B and C, respectively,are amplified in preamplifiers 30, 32 and 34, respectively, and appliedto separate channels of eight channel multiplexer 36.

Arterial and veinal blood pressure transducers 38 and 40 sense bloodpressure and provide through preamplifiers 42 and 44 blood pressuresignals labeled D and E to separate channel inputs of multiplexer 36.

Temperature of a patient is typically sensed by both a skin temperatureprobe 46 and internal temperature probe 48 in conjunction with bridgenetworks 50 and 52, respectively, and the resulting signal outputs fedas inputs G and H to separate channels of multiplexer 36. As anauxiliary or reserve function channel, any appropriate transducer 54 maybe employed together with any appropriate signal conditioning device 56and applied as an auxiliary input F to multiplexer 36. For simplicity ofdesignation, the channels of multiplexer 36 are also referred to asA-I-I in accordance with the signal designations.

Multiplexer 36 functions to sample each of the input channelssequentially at a rate which provides for each channel to be sampled fora period of 250 microseconds permitting sampling of all eight channelsin a period of 2,000 microseconds, a sampling rate of 500 times persecond. Multiplexer 36 is driven or controlled by gating pulsesgenerated by sync generator and logic control 58 of analog-to-digitalconverter 60. The time shared outputs of multiplexer 36 are indifferential signal form and are fed to signal conditioner 62. Thefunction of signal conditioner 62 is to properly scale the various typesof signal information applied to it for analog-todigital conversion. Forexample, the three ECG signals are referenced at 2% volts, that is withno signal provided by transducers 22, 24 or 26, the conditioned signalshave a value of 2% volts. The same reference is applied to the auxiliaryor multipurpose open channel F. The blood pressure channels arereferenced at 0, that is with a 0 input on blood pressure channels F andE, the output of signal conditioner 62 is also zero. Similarly, thetemperature channels G and H are referenced with respect to and nobiasing, or addition of bias is effected. Conditioning is achieved byapplying from reference level circuit 64 to signal conditioner 62 areference voltage of 2% volts, or other appropriate level, during andonly during'the required periods, that is during the periods 5 channelsA-C and F are being passed by multiplexer 36. At other times thereference voltage is held at zero.,Reference level circuit 64 iscontrolled by an appropriate train of control pulses from sync generatorand logic control 58 of analog-todigital converter 60 to accomplishsynchronized application of reference voltages. 4

The output of signal conditioner 62 is fed to analog-todigital converter60 which converts the Pulse Amplitude Modulated (PAM) output of signalconditioner 62 to digital form, having for example, a maximum scaleoutput of 5.1 volts. A -bit digital word system is used in which thefirst eight bits are representative of the converted analog informationand the last two bits accomplish word and frame identification,respectively. The duration of a bit determines the presence or absenceof a coded or weighted digit, with a bit of 6 microsecond durationrepresenting a 0" and a bit of 18 microseconds representing a 1. The endof a word is marked by a 12 microsecond pulse in the ninth bit positiongand the presence of a 12 microsecond pulse in both the ninth and 10thbit positions mark the end of a frame. A word corresponds to onesampling of the amplitude of one of the physiological conditions beingsampled and a frame correspond to one complete set of words or set ofsamplings of the physiological conditions being monitored.

The output of analog-to-digital converter 60 is applied to and pulsecode modulates FM transmitter 66. The presence of a 6 microsecond pulseshifts the carrier about 100 kHz., a 12 microsecond pulse shifts itabout 100 kHz. and a 18 microsecond pulse shifts the carrier about 100kHz. Typically, the carrier frequency of a transmitter 66 would be inthe FM broadcast range of 88 to 108 MHz. By the use of pulse code widthmodulation, extremely accurate and dependable intrahospitalcommunications are achieved despite the presence of substantialradiation from other equipment such as X-ray and diathermy machines.

Blood pressure transducers 38 and 40 typically require an operating biascurrent of approximately 10 ma. each and as a feature of this inventionthe operating bias is keyed on only during the periods when channels Dand E are gated open by keying pulses d, and e,,, respectively, frommultiplexer 36 by switching means integral with probe, or probeassemblies 38 and 40. Thus operating power is applied to each oftransducers 38 and 40 for one-eighth of the time normally required, thussignificantly reducing the overall operating power requirements for apatient unit. In fact, the reduction is approximately 40 percent.

FIG. 3 shows the circuit arrangement of central monitor 12. As statedabove, it is basically divided between Radio Receiving Section 14, EveryPatient Continuous Monitoring" Section 16, Patients Selective Section"18 and Cathode-Ray Display 20. Radio receiving section 14 consists ofeight radio receivers, each tuned to the frequency channel of a likedesignated patient unit (FIG. 1). It has been determined that clear FMbroadcast channels (for the particular locale) provide excellentcommunication channels with very low power. Each Every PatientContinuous Monitoring Section 16 receives an appropriate receiver outputwhich is applied to a digital-toanalog converter 68. The one shown isresponsive to 5 receiver No. 1 and processes data from patient 1. Herethe digitally coded data from a transmitter 66, and received by ReceiverNo. 1, is converted to analog form and the output of each data channelis appropriately sampled, held between samples and filtered to reproducethe original measurements. As shown, five of the measurements areutilized in this section, ECG-A, ECG-B, ECG-C, arterial blood pressure Dand indirect blood pressure E (which could be used for other data). Theother measurement channels F, G, and H are available as needed foranalog analysis. One of the ECG signals, ECG-A, is

applied to tachometer and meter driver 70 and thence tocounts-per-minute meter 72 for direct readout of heart rate. Meter 72also includes upper and lower limits which power, respectively, upperand lower limit alarm lights 74 and 76. This permits the preset ofcritical limits for a given patient as determined by his doctor and thusprovides selective critical care for that patient. As a still furtheraid to the detection of a dangerous change in heart condition, a heartsignal output, such as from ECG-A, is fed to preshock detector and alarm78, which detects the presence of higher than normal voltages andenergizes alarm light 79.

Continuous visual observation of any one of a particular patientscondition as provided by any one of the outputs of digital-to-analogconverter 68 is achieved by connecting the output to cathode-ray display20 which has an allotted space slot for each patient as illustrated inFIG. 4. As shown in FIG. 3, switch is arranged to selectively connectany one of outputs A-E to the patient No. 1 input of cathode-ray display20.

ln addition to the graphical display of blood pressure, outputs D and Eof digital-to-analog converter 68, blood pressure is also indicated onmeter 81 which includes adjustable upper systolic and lower systoliclimit detection which energizes a low or high limit alarm, lights 82 or83 as the case may be, if a preset value is passed. in addition,systolic detector and diastolic detectors 84 and 86 and which controlmeter 81 also provide an output in the form of an electrical pulse todecode for wor stage 88 of patient selective monitoring section 18indicating the time of occurrence of upper and lower peak values ofblood pressure which indications are used to identify in time theappropriate digital word carrying a precise value for such high or lowvalue. The operation of this portion of the system will be furtherdiscussed below.

As another mode of indicating selected outputs of digital-toanalogconverter 68, recorder 90 may be connected to continuously record anyone of these outputs.

Decimal readout of physiological conditions monitored by the system arecontrolled by patient control 92 responsive to patient selector 94, inPatient Selective Monitoring Section 18. For purposes of illustration,it will be assumed that patient No. 1 is selected. Patient control 92then connects an output from receiver 1 to binary to binary codeddecimal (BCO) converter 96 which, accordingly, provides as outputsD,E,G, and H decimally coded signals to like function decimal readouts,

5 the D output being fed to both systolic and disastolic blood pressurereadouts 98 and 100, respectively, the E output being fed to veinalblood pressure readout 102, the G output being fed to externaltemperature readout 104 and the H output being fed to internaltemperature readout 106. In addition, gating pulses, e,g and hcorresponding in time to the occurrence of like, but upper case,lettered data outputs are fed, respectively, to gates 108, 110 and 112to provide data bits to decimal readouts 102, 104 and 106 only duringthe precise times in which the data is accurate as determined by binaryto binary coded decimal converter 96. Precise readout of systolic anddiastolic blood pressure requires an indication not only of the time ofoccurrence of an accurate bit of data, but also the time when bloodpressure corresponds to a systolic or diastolic condition. Accordingly,decode for word" circuit 88, a switching circuit, receives systolic anddiastolic when pulses from systolic detector 84 and diastolic detector86, respectively, and applies same appropriately to AND-gates 114 and116. Gates 114 and 116 are also provided with word readout markingpulses d from binary to binary coded decimal converter 96. Whencoincident pulses are applied to one of the AND" gates a gating pulse isapplied to gates 118 or 120, as the case may be, and accurate decimalreadout of systolic or diastolic blood pressure on readouts 98 orobtained. Patient selection for decode for words circuit 88 iscontrolled by patient selector 94. Patient selector 94 also provides forautomatic cycling of the decimal readouts. This is accomplished byselecting the .r" condition on selector 94 which then causes the systemto decimally readout in sequence data derived from each patient.indication of the particular patient "um: A!!! being observed isprovided by illumination of numbers 122, a light for a particular numberbeing energized during the period in which data from a correspondingpatient is being read out.

The operation of this system has been generally described above. Patientunits and accompanying probes are initially placed on and with respectto each patient. Data from each patient is then transmitted via a pulsecode modulated PM link between patient units 10 and receiving section 14of central monitor 12. An output from each receiver is applied to thecorresponding analog section 16. The operator of the central controlmonitor visually scans periodically the traces on cathode-ray display 12corresponding to the physiological functions of each patient. Theoperator particularly selects between physiological signals to beobserved by selector switch 80. The operator also observes heart rate onmeter 72 and systolic and diastolic blood pressure on meters 81.Dangerous blood pressure excursions are indicated by preset warninglights 82 and 83 and a preshock condition by alarm 78. When desired, asfor example, when there is an indication of progressive changes in apatient, particular functions may be recorded on tape recorder 90.

The operator may also selectively observe decimal readouts for precisedetermination of blood pressure, including systolic and diastolic bloodpressure, for any patient. In addition, both external and internaltemperature are made decimally available for examination.

in summary. by means of reasonable attention and selection a singleoperator is able to provide intensive and extensive observation of anumber of patients, a feat not previously possible. It is thereforeconcluded that the inventors have provided a new and novel system formore complete patient care, and with substantially less personnel effortthan heretofore possible.

What is claimed as our invention is:

1. A physiological monitoring system for remotely monitoring a pluralityof physiological conditions of at least one hospitalized patientcomprising:

A. At least one patient unit for sensing a plurality of physiologicalconditions and providing electrical signals representative thereof, eachsaid circuit including at least one heart sensor, at least one bloodpressure sensor, and at least one temperature sensor and furtherincluding:

1. commutation means having an input channel for each sensed conditionand being responsive to said signals for providing a serial outputconsisting of repeated sequential samplings of said signals,

2. signal conditioning means responsive to the output of and operatingin synchronization with said commutation means for selectively adjustingthe reference level of the now serially arranged signals,

3. analog-to-digital translation means responsive to said signalconditioning means for providing a digitally encoded word signal foreach sample of a given physiological signal and for providing a signalindicating the completion of single word and the completion of a set ofwords; and

4. radio transmission means for transmitting said encoded word signalsby a pulse-code, frequency-modulated radio frequency carrier;

B. A central monitor for indicating physiological conditions from atleast one said patient unit and including:

1. receiving means including a radio receiver for each patient unit forreceiving a radio signal from a said patient unit,

2. digital-toanalog conversion means responsive to an output from eachsaid receiver for providing analog outputs including at least one heartresponsive signal and at least one blood pressure responsive signal,

3. cathode-ray tube means for selectively displaying at least one heartresponsive signal and at least one blood pressure responsive signal fromeach patient monitored,

I 4. heart rate means responsive to a said heart responsive signal of apatient for indicating the rate of heart beat of that patient,

5. preshock detection means responsive to the amplitude of a said heartresponsive signal for indicating the presence of overvoltage signals anda preshock conditron,

6. systolic detection and indicating means responsive to a bloodpressure signal output of said digital-to-analog converter for detectingand indicating maximum values of blood pressure,

7. diastolic detection and indicating means responsive to a bloodpressure signal output of said digital-to-analog converter for detectingand indicating minimum values of blood pressure,

8. binary to binary coded decimal conversion means responsive to aselected said receiving means for providing a first plurality of outputswherein at least one output is a decimally coded temperature signal, andfor providing a second plurality of outputs wherein at least one outputis a signal marking the period of accurate readout of blood pressuresignal and at least one said output is a signal marking the period ofaccurate readout of a said temperature signal,

9. decimally indicated systolic blood pressure indicating meanscomprising:

a. first systolic gating means responsive to the coincidence of anoutput from said systolic detection means marking the period ofoccurrence of a systolic condition and said output from said binary tobinary coded decimal conversion means marking the period of accuratereadout of a said blood pressure signal for providing a systolicoccurrence gating signal,

b. systolic decimal readout means,

0. second systolic gating means responsive to an output of said firstsystolic gating means and a said decimally coded blood pressure signalfrom said binary to binary coded decimal conversion means for providinga systolic blood pressure digitally encoded signal to said systolicdecimal readout means,

10. decimally indicated diastolic blood pressure indicating meanscomprising:

a. first diastolic gating means responsive to the coincidence of anoutput from said diastolic detection means marking the period ofoccurrence of a diastolic condition and a said output from said binaryto binary coded decimal conversion means marking the period of accuratereadout of a said blood pressure signal for providing a diastolicoccurrence gating signal,

. diastolic decimal readout means,

c. second diastolic gating means responsive to an output of said firstdiastolic gating means and a said decimally coded blood pressure signalfrom said binary to binary coded decimal conversion means for providinga diastolic blood pressure digitally encoded signal to said diastolicdecimal readout means,

1 l. at least one digital temperature readout means, and

12. gating means responsive to a said decimally coded temperature signaland a signal marking the period of accurate readout of said temperaturesignal for provid ing a digitally coded signal to said digitaltemperature readout means.

2. A physiological monitoring system as set forth in claim 1 wherein atleast one said blood pressure sensor requires an applied operating biasand said system further comprises means for providing said operatingbias only during the periods in which the output of said blood pressuresensor is being passed through said commutating means.

3. A physiological monitoring system as set forth in claim 1 whereinsaid central monitor further comprises recording means for selectivelyrecording at least one said signal.

1. A physiological monitoring system for remotely monitoring a pluralityof physiological conditions of at least one hospitalized patientcomprising: A. At least one patient unit for sensing a plurality ofphysiological conditions and providing electrical signals representativethereof, each said circuit including at least one heart sensor, at leastone blood pressure sensor, and at least one temperature sensor andfurther including:
 1. commutation means having an input channel for eachsensed condition and being responsive to said signals for providing aserial output consisting of repeated sequential samplings of saidsignals,
 2. signal conditioning means responsive to the output of andoperating in synchronization with said commutation means for selectivelyadjusting the reference level of the now serially arranged signals, 3.analog-to-digital translation means responsive to said signalconditioning means for providing a digitally encoded word signal foreach sample of a given physiological signal and for providing a signalindicating the completion of single word and the completion of a set ofwords; and
 4. radio transmission means for transmitting said encodedword signals by a pulse-code, frequency-modulated radio frequencycarrier; B. A central monitor for indicating physiological conditionsfrom at least one said patient unit and including:
 1. receiving meansincluding a radio receiver for each patient unit for receiving a radiosignal from a said patient unit,
 2. digital-to-analog conversion meansresponsive to an output from each said receiver for providing analogoutputs including at least one heart responsive signal and at least oneblood pressure responsive signal,
 3. cathode-ray tube means forselectively displaying at least one heart responsive signal and at leastone blood pressure responsive signal from each patient monitored, 4.heart rate means responsive to a said heart responsive signal of apatient for indicating the rate of heart beat of that patient, 5.preshock detection means responsive to the amplitude of a said heartresponsive signal for indicating the presence of overvoltage signals anda preshock condition,
 6. systolic detection and indicating meansresponsive to a blood pressure signal output of said digital-to-analogconverter for detecting and indicating maximum values of blood pressure,7. diastolic detection and indicating means responsive to a bloodpressure signal output of said digital-to-analog converter for detectingand indicating minimum values of blood pressure,
 8. binary to binarycoded decimal conversion means responsive to a selected said receivingmeans for providing a first plurality of outputs wherein at least oneoutput is a decimally coded temperature signal, and for providing asecond plurality of outputs wherein at least one output is a signalmarking the pEriod of accurate readout of blood pressure signal and atleast one said output is a signal marking the period of accurate readoutof a said temperature signal,
 9. decimally indicated systolic bloodpressure indicating means comprising: a. first systolic gating meansresponsive to the coincidence of an output from said systolic detectionmeans marking the period of occurrence of a systolic condition and saidoutput from said binary to binary coded decimal conversion means markingthe period of accurate readout of a said blood pressure signal forproviding a systolic occurrence gating signal, b. systolic decimalreadout means, c. second systolic gating means responsive to an outputof said first systolic gating means and a said decimally coded bloodpressure signal from said binary to binary coded decimal conversionmeans for providing a systolic blood pressure digitally encoded signalto said systolic decimal readout means,
 10. decimally indicateddiastolic blood pressure indicating means comprising: a. first diastolicgating means responsive to the coincidence of an output from saiddiastolic detection means marking the period of occurrence of adiastolic condition and a said output from said binary to binary codeddecimal conversion means marking the period of accurate readout of asaid blood pressure signal for providing a diastolic occurrence gatingsignal, b. diastolic decimal readout means, c. second diastolic gatingmeans responsive to an output of said first diastolic gating means and asaid decimally coded blood pressure signal from said binary to binarycoded decimal conversion means for providing a diastolic blood pressuredigitally encoded signal to said diastolic decimal readout means,
 11. atleast one digital temperature readout means, and
 12. gating meansresponsive to a said decimally coded temperature signal and a signalmarking the period of accurate readout of said temperature signal forproviding a digitally coded signal to said digital temperature readoutmeans.
 2. signal conditioning means responsive to the output of andoperating in synchronization with said commutation means for selectivelyadjusting the reference level of the now serially arranged signals,
 2. Aphysiological monitoring system as set forth in claim 1 wherein at leastone said blood pressure sensor requires an applied operating bias andsaid system further comprises means for providing said operating biasonly during the periods in which the output of said blood pressuresensor is being passed through said commutating means. 2.digital-to-analog conversion means responsive to an output from eachsaid receiver for providing analog outputs including at least one heartresponsive signal and at least one blood pressure responsive signal, 3.cathode-ray tube means for selectively displaying at least one heartresponsive signal and at least one blood pressure responsive signal fromeach patient monitored,
 3. A physiological monitoring system as setforth in claim 1 wherein said central monitor further comprisesrecording means for selectively recording at least one said signal. 3.analog-to-digital translation means responsive to said signalconditioning means for providing a digitally encoded word signal foreach sample of a given physiological signal and for providing a signalindicating the completion of single word and the completion of a set ofwords; and
 4. radio transmission means for transmitting said encodedword signals by a pulse-code, frequency-modulated radio frequencycarrier; B. A central monitor for indicating physiological conditionsfrom at least one said patient unit and including:
 4. heart rate meansresponsive to a said heart responsive signal of a patient for indicatingthe rate of heart beat of that patient,
 5. preshock detection meansresponsive to the amplitude of a said heart responsive signal forindicating the presence of overvoltage signals and a preshock condition,6. systolic detection and indicating means responsive to a bloodpressure signal output of said digital-to-analog converter for detectingand indicating maximum values of blood pressure,
 7. diastolic detectionand indicating means responsive to a blood pressure signal output ofsaid digital-to-analog converter for detecting and indicating minimumvalues of blood pressure,
 8. binary to binary coded decimal conversionmeans responsive to a selected said receiving means for providing afirst plurality of outputs wherein at least one output is a decimallycoded temperature signal, and for providing a second plurality ofoutputs wherein at least one output is a signal marking the pEriod ofaccurate readout of blood pressure signal and at least one said outputis a signal marking the period of accurate readout of a said temperaturesignal,
 9. decimally indicated systolic blood pressure indicating meanscomprising: a. first systolic gating means responsive to the coincidenceof an output from said systolic detection means marking the period ofoccurrence of a systolic condition and said output from said binary tobinary coded decimal conversion means marking the period of accuratereadout of a said blood pressure signal for providing a systolicoccurrence gating signal, b. systolic decimal readout means, c. secondsystolic gating means responsive to an output of said first systolicgating means and a said decimally coded blood pressure signal from saidbinary to binary coded decimal conversion means for providing a systolicblood pressure digitally encoded signal to said systolic decimal readoutmeans,
 10. decimally indicated diastolic blood pressure indicating meanscomprising: a. first diastolic gating means responsive to thecoincidence of an output from said diastolic detection means marking theperiod of occurrence of a diastolic condition and a said output fromsaid binary to binary coded decimal conversion means marking the periodof accurate readout of a said blood pressure signal for providing adiastolic occurrence gating signal, b. diastolic decimal readout means,c. second diastolic gating means responsive to an output of said firstdiastolic gating means and a said decimally coded blood pressure signalfrom said binary to binary coded decimal conversion means for providinga diastolic blood pressure digitally encoded signal to said diastolicdecimal readout means,
 11. at least one digital temperature readoutmeans, and
 12. gating means responsive to a said decimally codedtemperature signal and a signal marking the period of accurate readoutof said temperature signal for providing a digitally coded signal tosaid digital temperature readout means.